Locking device for door keys



- April 13,- 1943. w. E. AMOS LOCKING DEVICE FOR DOOR KEYS Filed Aug. 19. 1940 Patented Apr. 13, 1943 UNITED 2 Claims.

My invention relates to locking devices for door keys, and its principal object is to provide a simple and eflicient device which may be easily and quickly applied to the shank of a door knob and inserted through the loop or handle of the key to prevent the same from being turned from the outside to release the lock.

Another object of my invention is to provide a device of the character referred to which has sufficient strength to resist the various unlawful implements used by burglars and others to turn a key from the outside, and which can be made economically by modern production methods.

In order that my said invention may be thoroughly understood by those skilled in the art, I will now describe a preferred embodiment of the same, reference being had to the accompanying drawing, in which- Figure 1 is a front elevation showing my device applied to a conventional door knob, the parts being in the locked position.

Figure 2 is a side elevation of the same.

Figure 3 is a fragmentary elevation corresponding to Figure 1 showing the lower part of my device in the open or unlocked position.

Figure 4 is a fragmentary side elevation of the same.

Figure 5 is a fragmentary front elevation corresponding to Figure 3 but showing the device in a condition midway between the locked and unlocked positions, and Figure 6 is a side elevation.

Figure 7 is a fragmentary front elevation corresponding to Figure 1 showing a modified form of my device, and Figure 8 is a side elevation of the same.

Like characters designate corresponding parts throughout the several views.

In the drawing, Y designates a yoke formed from spring wire or other suitable material having at its upper end a pair of straight side members 2 which are connected at their upper end by a U-shaped portion 3 bent at right angles, as shown in Figures 1 and 2. The lower ends of the members 2 are bowed outwardly in arcuate .form as indicated at 3| so that they may pass easily over the door knob K, and these portions terminate in hooks 4 to which the main locking member or tongue 5 is hingedly connected. .The member 5, as shown in Figure 3, consists of a central U-shaped member 5| adapted to pass through the loop L of the key, and the legs of this member are bent outwardly in an angular direction as at 52 and then upwardly and outwardly as at 53, where they terminate in loops 5 5 through which the hooks 4 of the yoke pass.

In applying the device, the arcuate portions 3! of the yoke are passed over the door knob and then slid downwardly over the shank of the same until the parts occupy the relative positions shown in Figures 3 and 4 of the drawing. The tongue 5 is then turned upwardly into the position shown in Figures 5 and 6, and the yoke then raised by means of the projection 3 until the part 5! passes through the loop of the key, which then becomes looked as shown in Figures 1 and 2.

The device is released by pushing downwards upon the portion 3 of the yoke which causes the tongue 5 to be withdrawn from the loop of the key and the yoke is then raised and withdrawn over the door knob, as will be understood.

In the modification shown in Figures '7 and 8 of the drawing, the arcuate portions 31 are dispensed with, the ends of the members 2 being extended downwardly and terminating in pivots 2 I, said pivots being adapted to engage the loops 54 of the tongue 5 and be retained therein by the lateral extensions 22 (see Figure 8) when the parts are in the position shown. The loops 54 are, however, so proportioned that by rotating the tongue through a certain angle the members 2 may be detached from the latter. By this means the yoke may be slid vertically off and on the shank of the door knob, the tongue being placed in position under the loop L of the key when the yoke is in the proper position.

It should be noted that the vertical members 2 of the yoke Y are so arranged that the space between them is less than the diameter of the shank of the door knob, which prevents the device from being easily disengaged by any tool which might be inserted through the key hole from the outside.

Further, the yoke Y, being of resilient material, is initially so shaped that there is a constant force tending to spread the hooks 4 apart, and the hooks 4, as well as the loops 54 upon the member 5, are so shaped that this spreading force causes the said member to automatically move downwards from the position shown in Figures 5 and 6 to the position shown in Figures 3 and 4 as soon as the member 5| is withdrawn from the loop of the key, as hereinbefore described, so that the member 5 is then prevented from interfering with the normal turning of the key in the look.

It will be observed from the foregoing description and by reference to the drawing that I have provided a device which is well adapted to the purpose set forth, and at the same time is cheap to manufacture, being formed preferably from round spring wire, and while I have herein shown and described a preferred embodiment of my said invention, it will be readily understood by those skilled in the art to which the same pertains that various changes may be made in detail without departing from the spirit of my invention as defined in the appended claims.

Having thus described my said invention, what I claim and desire to secure by Letters Patent of the United States is:

l. A key locking device comprising a yoke-like structure having a pair of straight Side members connected at their upper ends by a handle portion disposed at right angles to said members and having at their lower ends a pair of arcuate members adapted to pass over a door knob and termiswivelly engaging the first-mentioned loops and' having a central U-shaped portion adapted to engage the handle of a key to lock the same against rotation.

2. A key locking device comprising a yoke-like structure having a pair of straight side members connected at their upper ends by a handle portion disposed at right angles to said members and having at their lower ends a pair of arcuate members adapted to pass over a door knob and terminating in closed loops; and a tongue having loops swivelly engaging the first-mentioned loops and having a central U-shaped portion adapted to engage the handle of a key to lock the same against rotation, said respective loops having co-acting inclined portions whereby the tongue is yieldably urged out of engagement with the handle of the key when the yoke-like structure is depressed by. means of the handle portion.

WILLIAM E. AMOS. 

